Wet connection system for downhole equipment

Abstract

A wet connection system suitable for use in hydrocarbon wells is formed from one or more elongated, small diameter conduits which extend down the wellbore and which terminate adjacent a locating structure on the production tubing. Equipment deployed at the locating structure is connected to one or more self supporting conductors which extend down the conduits from the wellhead. Preferably the conductors are retractable and the conduits are sealingly connected to the equipment, allowing the equipment and conductors to be deployed and recovered independently of each other and to be flushed with dielectric oil pumped down the conduits after re-connection.

Claims

1. A system for connecting a conductor to equipment deployed down a borehole, including tubing extending down the borehole from an upper end of the borehole; an annularly positioned electrical connector disposed on the lower end of the tubing, at least one elongated conductor disposed in the annulus between the borehole and the tubing extending from the upper end of the borehole to the annularly positioned electrical connector, the conductor being connectable to the equipment in the annularly positioned electrical connector; an electrically powered machine capable of being lowered down the tubing, the electrically powered machine including a radially spaced connector arm, such that the electrically powered machine can be oriented at the bottom end of the tubing so that it coincides with the annularly positioned electrical connector to make electrical connection to the annularly positioned electrical connector, and is secured by anchors, wherein the anchors include frangible parts that may be broken in order to release the electrically powered machine.

2. A system according to claim 1, wherein the inner surface of the tubing and the outer surface of the electrically powered machine are shaped such that the electrically powered machine is oriented as it is lowered in the tubing.

3. A system according to claim 1, wherein the electrically powered machine is raised after being lowered to make electrical connection to the annularly positioned electrical connector.

4. A system according to claim 1, wherein the elongated conductor is disposed in a conduit extending from the upper end of the borehole to the annularly positioned electrical connector.

5. A system according to claim 4, wherein the conduit is sealingly connectable to the equipment when adjacent to the annularly positioned electrical connector.

6. A system according to claim 5, wherein the conductor is connectable and disconnectable to and from the equipment when the conduit is sealingly connected to the equipment.

7. A system according to claim 4, wherein the conductor is slidably disposed inside the conduit.

8. A system according to claim 7, wherein the conductor is slidably removable from the conduit via the upper end of the borehole.

9. A system according to claim 7, wherein a lower end of the conductor is flushed with flurinert, 6.4 sp. Gr. or another dielectric fluid.

10. A system according to claim 7 wherein the upper end of the conductor is engaged with a wet connector mounted in a Christmas tree.

11. A system according to claim 7 wherein the upper end of the conductor passes through a Christmas tree to an electrical bulkhead.

12. A system according to claim 4, wherein the conductor is an electrical conductor.

13. A system according to claim 11, wherein the conductor is copper clad steel.

14. A system according to claim 4, wherein a clearance gap is filled with a protective fluid.

15. A system according to claim 4, wherein a clearance gap is sealed proximate the annularly positioned electrical connector.

16. A system according to claim 4, wherein the borehole includes a fixed casing defining a wellbore, and the tubing is deployed within the wellbore.

17. A system according to claim 16, wherein the conduit is supported by attachment to the tubing between the upper end of the borehole and the annularly positioned electrical connector.

18. A system according to claim 1, wherein the frangible parts include a frangible pin that is sheared when a jarring force is applied to the tubing.

Description

(1) Some illustrative embodiments of the invention will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which:

(2) FIG. 1 is a longitudinal section through a borehole in accordance with an annular conductor mounted to production tubing and its lower end terminated into the upper side of a structure in the production tubing.

(3) FIG. 2 is a similar view to FIG. 1 with an ESP installed inside the production tubing and docked into the wet connector located in the structure in the production tubing.

(4) FIG. 3 is a section side view of a well head showing one of the annular conductors penetrating the tubing hanger and an upper wet connector attached to the annular conductor.

(5) FIG. 4 is a similar view to FIG. 3 with the annular conductor being retrieved through pressure control equipment.

(6) FIG. 5 is an end cross section of the production casing, production tubing and annular mounted power cable.

(7) FIG. 6 is a side cross section of a subsea horizontal Christmas tree with an annular mounted power cable passing through the tubing hanger and connected to an electrical wet connector mounted in the tree cap.

(8) FIG. 7 is an end cross section of the production casing, production tubing and annular mounted power cable.

(9) FIG. 8 is a close-up section end view of the power cable mounted inside the annularly mounted coiled tubing.

(10) Referring to FIGS. 1 and 2, there is shown a well with casing 1 inside which is set production tubing 2 stung into a polished bore receptacle 3 of a packer 4. On the outside of the tubing are three tubes 5 though which a conductor 6, which is terminated at the production tubing hanger 7 and connects to the outside world via an electrical wet connector 8. At its lower end it connects into a powered device such as an electrical submersible pump (ESP) 9 via a downhole electrical wet connector 10. The through tubing retrievable ESP is lowered past the structure in the production tubing 11, it is then picked up and orientates its plug arm 12 into the annularly positioned electrical connector using proximity sensors or other means. At an overpull of 200 lbs the wet connector is fully engaged, and during the engagement process the electrical parts are flushed with flurinert or equivalent dielectric fluid. At the same time during the overpull, frangible anchors 13 are deployed which locate in the profile 14.

(11) The plug arm is extends radially from the ESP, and once the plug arm is beneath the lower edge of the tubing, there is enough room between the sides of the ESP and the tubing for the plug arm to be maneuvered outside of the tubing wall by displacing the ESP from the tubings centre axis for the plug arm to be oriented beneath the electrical connector.

(12) In the event that there is a fault with the ESP motor on the half of the wet connector attached to the motor, a GS running tool is lowered into the well and locates in an internal profile at the pump discharge 15. A downward jar is activated which shear pins in the frangible anchors 13. The GS running tool is then picked up with an over pull of 300 lbs. This releases the anchors and the whole assembly can then be lowered, undocking it from the wet connector and enabling the assembly to be retrieved back to surface for repair or service or replacement.

(13) In the event that there is a fault with the conductor in the annulus or wet connector at its lower most end, the surface wet connector 8 is disengaged from an electrical bulkhead 16 and a retrieval tool 17 is lowered into the Christmas tree through pressure control equipment not shown and attaches itself to the cable head 18 and removes the conductor, for repair service or replacement.

(14) FIGS. 3 to 5 show a surface arrangement for a typical land Christmas tree, the conductors 20 are mounted into individual tubes 21 which pass through the tubing hanger and enable the surface wet connector 23 to engage with the upper half of the conductor protruding above the hanger 24. The surface wet connector includes flow area 22 around the conductor 25 to enable a dielectric fluid to be pumped into around the electrical wet connector. In the event the conductor has to be removed, pressure control equipment 26 is installed and a retrieval tool lowered 27 into it to fish the conductor 28. A plug 29 may or may not be used to isolate the production tubing during this operation.

(15) FIGS. 6 to 8 show a typical subsea horizontal tree arrangement. The annular cable could be, for example, a section of coiled tubing as described in more detail in patent number U.S. Pat. No. 7,541,543 (though other suitable cables may be used). Such a cable can support its own weight and has a metal external layer 40, with three electrical conductors 41 twisted together and held in a jacket 42. This cable is located inside a section of coiled tubing 43 which is attached to the outside surface of the production tubing 44. During service the tree cap 45 is removed, and the wet connector 46 is removed with it. Pressure control equipment is then installed. Full access to the top of the tubing hanger 47 is now possible. It is possible to access either the externally run power cable or the internally run ESP.